Love how nobody got the joke
When DST ends you set your clock back 1 hour (or it does it automatically nowadays) in the middle of the night, gaining 1 hour of extra sleep
The joke here is that the guy did the same for Leap Day, setting his clock back 24 hours and gaining 24 hours of sleep, so when his boss called at 2pm he was in the middle of his ~32h night
"Energy contained in coal" doesn’t make any sense. Is it "energy we could get from burning coal if it was 100% efficient"? "Energy we could get from coal if we could use it in a nuclear reaction"?
Coal (anything) doesn’t "contain" energy. We can transform some things, and some transformations produce energy in some form or another.
The upper line of this graph should be labeled "total energy liberated by burning coal" and the lower one "useful energy liberated by burning coal".